The objective of the proposed research is to implement the use of an optical microring resonator bioanalysis platform to profile the phosphorylated proteins present in model cell lines and real-life glioblastoma multiforme (GBM) tumor biopsy samples. The inherent advantages of this multiparameter, label-free technology, with increased sensitivity, seeks to advance current diagnostic capabilities by reducing sample size requirements while simultaneously, evaluating on an individual basis, post-translational modifications that lead to the deregulation of signal transduction pathways (STPs) involved in the development and progression of GBM. Incorporating phospho-specific antibodies and the optical bioanalysis platform aims to reduce the severity of the procedure for sample obtainment by replacing standard immunohistochemical analysis of paraffin-embedded tumor biopsy samples with less invasive skinny-needle biopsies. This platform will also serve to increase the specificity of GBM treatment procedures by determining the deregulation of various STPs and incorporating the right inhibitor(s) for the patient. This research proposes to determine relative protein expression in six model cell lines transfected to have over-expression of PTEN, EGFR and EGFRvIII (separately and in combination), using the optical bioanalysis platform. This research plan is then expanded to monitor other downstream signal transduction cascades involving proteins such as PI3K, Akt, mTOR and MAPK/ERK from the same six cell lines. The affect of individual protein kinases, as well as individual and combinatorial therapies will also be studied on these same cell lines. Finally, this research anticipates the ability to monitor the phosphoproteins, effectively predicting the signal STP deregulation, responsible for the development of GBM in patients from which paraffin-embedded tumor biopsy tissues are obtained.